The present application claims the priority of the commonly owned copending German patent application Serial No. 101 00 664.0 filed Jan. 9, 2001. The disclosure of the above-referenced German patent application, as well as that of each US and foreign patent and patent application identified in the specification of the present application, is incorporated herein by reference.
The present invention relates to improvements in methods of and in apparatus for testing materials for the presence or absence of impurities and/or other foreign matter, for example, to methods of and to apparatus for detecting the presence (if any) of one or more second (foreign) materials or substances in a body or mass which consists primarily of a first (particulate) material. More particularly, the present invention relates to improvements in methods of and in apparatus for monitoring or testing or examining a mass normally consisting of a first material for the presence or absence of one or more second materials (hereinafter often called impurities for short) by resorting to a microwave field which is influenced by the impurities contained in the first material when the impurities-containing first material is introduced into the range of the microwave field.
An example of a first material which is or which might be likely to contain one or more impurities (such as metallic or plastic particles) is tobacco, e.g., the so-called rod-like filler of a running continuous cigarette rod or the fillers of discrete cigarettes running endwise or sideways in a cigarette making and/or processing machine. It is important to detect the presence of impurities in tobacco which is processed in modern high-speed machines or apparatus designed to turn out and/or to automatically process huge quantities of smokers"" products per unit of time. Certain machines or apparatus of such character are set up to subject a running mass or flow or a plurality of discrete masses or flows of comminuted natural, artificial and/or reconstituted tobacco to a series of successive treatments by resorting to belt conveyors, chain conveyors or analogous transporting means which advance tobacco between various stations or units, storage facilities and/or others.
It is inevitable or at least highly likely that the treatment of tobacco and/or of tobacco-containing products or similar products or commodities of the tobacco processing industry (e.g., filter material for tobacco smoke which is processed in filter rod making, filter cigarette making and similar units) results in or causes the introduction of impurities into tobacco, filter material and/or other primary or first materials. The presence of metallic particles, plastic particles and/or other impurities in plain or filter cigarettes and/or other finished smokers"" products can adversely influence the appearance, the taste, the rate of combustion and/or other characteristics of such products. Therefore, the relevant industries are continuously seeking to arrive at methods and apparatus for reliably detecting impurities in smokers"" products, and especially at improved methods and apparatus which can be put to use in modern high-speed machines (such as cigarette or filter cigarette making machines) that are capable of detecting impurities and/or of preventing introduction of impurities without necessitating a deceleration of such machines and without adversely affecting the appearance, the taste, the quality and/or other desirable characteristics or parameters of the products. The same holds true for the methods of and for the apparatus for mass-producing numerous other commodities, e.g., the aforementioned filter rods for tobacco smoke, filter rod sections and/or others.
Conventional undertakings to detect impurities in a primary or first material include numerous optical processes one step of which involves advancing the primary material along a path wherein the material is converted into a thin (single-stratum) layer. The exposed surface of the layer is photographed by one or more cameras and the thus obtained pictures are processed for the purpose of detecting and pinpointing foreign bodies (impurities) preparatory to their removal or expulsion from the layer. A drawback of such processes is that the equipment which is necessary for their practice is bulky and that such equipment can be put to use only during initial processing, e.g., during treatment of tobacco or filter material prior to entry into a cigarette rod making, filter rod making or an analogous machine. Consequently, the just described processes and apparatus cannot be resorted to for the detection of impurities which enter the primary material in a cigarette making, filter rod making or analogous machine, namely subsequent to confinement of the fillers of cigarettes, filter mouthpieces or the like in tubular wrappers consisting of or containing cigarette paper, artificial cork, tipping paper or the like.
In order to overcome the shortcomings of processes which are effective only during preliminary treatment of primary material (e.g., during transport of tobacco or filter material for tobacco smoke into a cigarette rod making or filter rod making machine), many machines of such character embody or are combined or associated with (a) suitable sifting devices which are capable of removing from the flow (stream) of tobacco or from the flow (tow) of filter material for tobacco smoke entering a cigarette maker or a filter rod maker certain heavier particles (such as tobacco ribs) and/or (b) with metal detectors (e.g., magnets) capable of detecting and/or detecting and segregating defective articles such as plain or filter cigarettes or filter rod sections. A drawback of the just discussed undertakings is that they can detect and/or remove only certain types of impurities so that, unless combined with sifting or the like, each such undertaking can ensure only the detection and segregation of a relatively low percentage of all impurities.
Certain additional presently known processes and apparatus for the detection of impurities rely upon the utilization of microwaves which are resorted to for the monitoring of specific parameters (such as the density and/or the moisture content) of finished or semifinished smokers"" products, for example, a continuous cigarette rod and/or discrete plain or filter cigarettes. An advantage of such undertakings is that they can furnish information with a very high degree of accuracy. Their effectiveness is attributable to the fact that the primary material (such as tobacco) is a satisfactory dielectric and highly hygroscopic so that it can contain a relatively high percentage of water (e.g., between about 10 and 20 percent by weight). In addition, water is also a highly satisfactory dielectric substance and, due to pronounced mobility of the molecular dipoles, exhibits a high loss factor at microwave frequencies. Such characteristics enable tobacco to exert a pronounced influence upon a microwave field, and this influence renders it possible to adequately distinguish between water and dry tobacco. Reference may be had to the disclosure in U.S. Pat. No. 4,707,652 granted Nov. 17, 1987 to Lowitz for xe2x80x9cIMPURITY DETECTOR MEASURING PARALLEL POLARIZED SCATTERED ELECTROMAGNETIC RADIATIONxe2x80x9d. The method which is disclosed in this patent involves a determination of abnormalities in spatial scattering of a microwave field by a tobacco sample to thus detect the presence or absence of impurities, such as metallic or plastic substances. The patented process is suitable for experimental practice in a laboratory, and its operation is satisfactory as long as the relative speed between the monitoring equipment and a sample is relatively low, i.e., such process cannot be resorted to in a high-speed machine, e.g., in a cigarette maker which turns out cigarettes in the range of up to 20,000 per minute.
An object of the invention is to provide a novel and improved method of at least detecting but preferably of detecting and segregating impurities which are randomly distributed in a primary (first) material or substance.
Another object of the invention is to provide a process which can be practiced by resorting to a relatively simple and inexpensive but highly reliable apparatus.
A further object of the instant invention is to provide a method which can be practiced while the material to be monitored for the presence of impurities is being advanced at a low speed as well as when the relative movement between such material and the detecting instrumentalities takes place at a high or extremely high speed.
An additional object of the invention is to provide a method which can be practiced for the detection of one or more types of impurities in shaped smokers"" products (such as plain or filter cigarettes, continuous cigarette rods, continuous rods containing filter material for tobacco smoke and/or filter rod sections) being turned out or processed in modern high-speed machines such as cigarette makers, filter cigarette makers, filter rod makers and/or others.
Still another object of the present invention is to provide a method which can be resorted to for the detection of presence of one or more impurities in rod-shaped products of the tobacco processing industry with a heretofore unmatched degree of accuracy and reliability.
A further object of the invention is to provide a method which can be practiced upon completion of relatively simple and inexpensive modifications of existing types of machines for the making of smokers"" products including plain cigarettes, cigarillos, cigars or the like, filter cigarettes, cigars, cigarillos or the like, filter mouthpieces for tobacco smoke, continuous tobacco-containing rods, continuous rods containing filter material for tobacco smoke and the like.
Another object of our invention is to provide a novel and improved apparatus for the practice of the above outlined method.
An additional object of the present invention is to provide an apparatus which can be combined with or incorporated into existing mass producing machines or production lines for the making of smokers"" products, components of smokers"" products as well as many other products which may but need not have any relationship with smoking.
Still another object of the invention is to provide a novel and improved impurities detecting apparatus which utilizes electromagnetic radiation.
A further object of the present invention is to provide a novel and improved method which, in addition to being capable of detecting impurities (such as foreign objects in a wrapped or unwrapped mass or flow of solid particles) can simultaneously serve for monitoring other (such as desirable) characteristics of commodities which are being turned out at a high or extremely high rate or frequency.
Another object of the invention is to provide an apparatus which treats the materials or commodities gently, which occupies a small amount of space in a manufacturing plant, which can be put to use in conjunction with existing types of tobacco processing and related or unrelated plants, and which contributes significantly to the appearance as well as to the taste and/or other desirable characteristics of the ultimate products.
An additional object of the invention is to provide a novel and improved cigarette making or filter rod making machine which embodies the above outlined apparatus.
One feature of the present invention resides in the provision of a method of testing a mass consisting at least primarily (i.e., at times primarily and at times exclusively) of a first material (e.g., shredded tobacco) for the presence of at least one second material (e.g., impurities including particles of metallic material, plastic material or the like). The improved method comprises the steps of establishing and maintaining a microwave field, introducing the mass into the range of the microwave field so that the microwave field is influenced by the mass (the introducing step can include moving the mass relative to the microwave field and/or vice versa), and analyzing the influence of the mass upon the microwave field. The analyzing step includes simultaneously measuring the actual values of a first and a second characteristic of the microwave field, selecting an acceptable value range for the actual values, ascertaining whether the actual values are within the acceptable range, and generating signals when the actual values are outside of the acceptable range.
The acceptable range encompasses or should encompass measured values of first and second characteristics of the microwave field when such field is influenced by a mass which contains only the first material.
The actual values are outside of the acceptable rangexe2x80x94to thus initiate the generation of signalsxe2x80x94when the mass which is being introduced into the range of the microwave field contains the at least one second material.
The mass can include or constitute a stream or flow, and the introducing step of such method can include moving the stream through the microwave field.
For example, the mass can consist at least of the first material, of a wrapper (such as a tubular wrapper) for the first material, and also possibly or potentially of at least one second material which, if present in the mass, is or can be randomly distributed in the first material.
As already mentioned hereinbefore, the first material is or can be a material of the tobacco processing industry, e.g., a smokable material (such as shredded tobacco) and/or filter material (such as acetate fibers, charcoal, etc.) for tobacco smoke.
The improved method can further comprise the steps of conveying the mass through the microwave field along a predetermined path, subdividing the mass in the path into a plurality of sections, and utilizing the signals (if and when generated) to segregate from the path those sections of the mass the introduction of which into the range of the microwave field has resulted in the generation of signals. The mass which is being conveyed along the aforementioned path can include the filler of a continuous cigarette rod or the filler of a continuous filter rod, and the subdividing step can include subdividing the cigarette rod or the filter rod into plain cigarettes or filter rod sections of unit or multiple unit length. The segregating step can include expulsion of plain cigarettes or filter rod sections from the path by resorting to a pneumatic, a mechanical or any other suitable segregating device.
Alternatively, the introducing step can include imparting to the mass the shape of a stream and conveying the stream in a predetermined direction along a path extending through the microwave field, confining the stream in a wrapping material upstream of the microwave field (as seen in the predetermined direction), and subdividing the wrapping material and the first material therein into a succession of discrete sections (e.g., plain cigarettes or filter rod sections of unit length or multiple unit length). When a signal is generated, it is utilized to segregate from the path discrete sections which contain second material. As already mentioned hereinbefore, each discrete section can include a rod-shaped smokers"" product having a rod-like filler and a tubular wrapper for the filler. The wrapper can consist of cigarette paper, imitation cork, so-called tipping paper which is utilized to unite cigarettes with filter mouthpieces and/or others.
The step of selecting an acceptable value range for the actual values can include introducing into the microwave field a sample mass which is devoid of the at least one second material (i.e., which consists exclusively of first material), examining the sample mass while such sample mass is within the microwave field, and utilizing the examining step to select the acceptable value range.
In accordance with an advantageous additional feature of the invention, the improved method can include the step of utilizing the measured actual values of the first and second characteristics of the microwave field for a determination of a characteristic of the mass other than potential presence of at least one second material. If the first material contains tobacco, the tobacco characteristic other than the potential presence of one or more second materials therein can include the density and/or the moisture content of tobacco.
Another feature of the present invention resides in the provision of an apparatus for testing a mass consisting at least primarily (but frequently or normally exclusively) of a first material for the presence of impurities (materials other than the first material). The improved apparatus comprises means for establishing and maintaining a microwave field, means for moving the mass and/or the microwave field relative to each other so that the microwave field is influenced by the mass, and means for analyzing the influence of the mass upon the microwave field. The analyzing means can include means for simultaneously measuring the actual values of first and second characteristics of the microwave field, means for selecting an acceptable value range for the actual ranges, means for ascertaining whether the actual values are within the acceptable range, and means for generating signals when the actual values are outside of the acceptable range as a result of the influence of impurities upon the microwave field.
The moving means can include means for moving an elongated flow of the mass along an elongated path a portion of which extends through the microwave field.
The apparatus can further comprise means for segregating (in respose to the signals) from the mass those portions which contain one or more impurities (e.g., metallic and/or plastic articles or particles).
The first material is or can be a material of the tobacco processing industry.
The apparatus can further comprise means for processing the actual values for the determination of one, two or more characteristics (such as the density and/or the moisture content) of first material other than the presence or absence of impurities.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and the modes of assembling, installing and utilizing the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.